Electronic devices (e.g. telecommunications device) that generate acoustic output (e.g. human speech) through a speaker typically comprise a housing having a speaker port and a speaker mounted within the housing in alignment with the speaker port. The term “speaker port” refers to aperture(s) or other structure that serve(s) as a pathway for sound from a transducer or diaphragm of the speaker (e.g. a hole or set of holes in the receiver portion of a cellular telephone). When using such an electronic device, a user may need to situate the speaker port near his or her ear so as to be able to hear the acoustic output. There are many different orientations in which the user may hold the device near his or her ear. For example, the user may press the speaker port against his or her ear such that his ear substantially surrounds the speaker port. In that case, the speaker plays into a small contained volume of air within the ear cavity. This is known as a sealed condition or as a “high degree of seal”. Alternatively, the user may only touch part of his ear to the speaker port such that the speaker is substantially open to the environment. In that case, the speaker plays into a much larger volume of air. This is known as a leak condition or as a “low degree of seal”.
A listener may perceive a change in the acoustic output of a speaker depending upon whether a leak or sealed condition exists. In the leak condition, a listener may perceive a loss of lower frequencies. Conversely, in a sealed condition, the listener may perceive an amplification of lower frequencies.
It has been proposed to distinguish between a sealed and leak condition by detecting the degree of movement of a speaker diaphragm as the speaker generates acoustic output. In a sealed condition, the diaphragm is more resistant to movement than in a leak condition. Thus, by detecting the degree of movement of the diaphragm, it may be possible to distinguish between the two conditions. In practice, however, detecting the degree of movement of the diaphragm may not be easily realizable. Because the degree of movement of the diaphragm is very slight, detecting fine differences in amplitude of a vibrating diaphragm may be problematic. This problem may be especially pronounced in the context of miniature speakers such as those found in mobile telecommunications devices. Moreover, different speakers, and even different models of the same type of speaker, may possess different characteristics of movement and therefore, knowledge of the characteristics of a particular speaker is often required.
An alternative approach for distinguishing between the sealed and leak conditions would be desirable. It would also be desirable to address the perceived degradation of sound quality that may result from these conditions.